A microcomputer-based measurement system of water stress in higher plants

Abstract

This paper describes a microcomputer-based system of continuously measuring water stress in plants in a non-destructive fashion. Water stress is estimated from the daily shrinkage-swelling behaviour of organs (trunk, branch, stem or fruits). Variations in size are measured by a displacement transducer (in this case a Linear Variable Differential transformer, LVDT) connected to a logger. The data recorded by the logger are transferred to a microcomputer to be processed and to calculate (a) maximum daily shrinkage which is used as an indicator of water stress, and (b) the change in mean diameter over a period of a few days in order to indicate growth rate. This system could be useful for agronomists testing irrigation regimes and for plant physiologists in search of a non-destructive method of recording water stress under field conditions.